Treated artificial thread and method of producing same



- The said threads (silk) are characterized by a often 4 to 6 grams per denier and more, but also Patented Mar. 29, 1938 'PMENT OFFICE I OD OF PRODUCING SAME TREATED Am an. THREAD AND ME'IfH- Leon Lilienfeld, Vienna, Austria N o Drawing.

Application October 25, 1934, Se-

rial No. 750,017. In. Austria June 12, 1926- s olaims. "(01. 8-20) The present application is in part a continu-.

ation of and in part an improvement upon and modification of the disclosure of my copending cases 186,575 filed April 25, 1927 and 367,148 filed May 29, 1929 (now Patents 1,989,098 and 1,989,099, respectively). In said prior cases I have described the treatment of viscose threads (in-- cluding viscose silk) made by contacting a shaped stream of viscose with a strong mineral acid, e. g. H2504 of or stronger and preferably H2504 of or stronger, or other acids of like strength, said threads or silk being generally known in the industry as Liiienfeld thread or Lilienfeld silk. Such products can be made according to the disclosure of my U. S. Patents 1,683,199 (Reissue 18,170), 1,683,200, 1,820,811, 1,881,740 and 1,881,742, and the corresponding foreign patents.

dry tenacity exceeding 2 grams per denier, and

by a low degree of extensibility, this latter being a drawback which for some time militated against an e'xtensiye use of such strong threads. The

-' I silky feel. 1

In accordance withthe disclosure of Ser. No. 186,575, I have found that the extensibility'can be substantially increased by treating the Lilien feld threads with a mercerizing agent such as NaOH solution of 15 to 18% strength or stronger, and allowing shrinking to take place during said treatment. v

In,Ser. No. 367,148, I have found similar results to be effected by the similar use of NaOH solutions of 2 to 5% strength. In said case it was also stated that NaOH solutions of over 5% and below 15%, although they would cause an increase in extensibility, would also cause a great loss in some of the other useful properties, such as luster, soft silky feel, dry and wet tenacity, etc. "It has now been found, and this constitutes the basis of the present case, that NaOH solutions of over 5% and below 10% strength, and particularly NaOH solutions'of between about 5.4% and about 9%, are usable in the treatment, and that the decrease in tenacity (wet and dry) is usually not excessive, and the loss in'silky feel is sometimes only slight and sometimes negligible, but the loss of luster is sometimes rather great. And with solutions of about 6 to 7% the loss in tenacity and'in soft silky feel can be bothv very low. In fact the loss in tenacity in some cases, when using NaOH solution of about 6-7% maybe not substantially greater than the corresponding loss when employing NaOH solutions of 18-25% strength.

I call attention also to the fact that the thread (silk) produced on a factory scale is in most cases, injured less by treatment with NaOH solutions of this order of concentration, than is the thread (silk) produced in the laboratory.

While I have above referred to the use of alkali metal hydroxide and alkali metal sulphide, and that in such cases, and the increase in extensibility can often be produced simultaneously with the desulphurization of the'threads. The threads can treated before or after desulphurization, bleaching and/or drying.

The treatment can be conducted as in the prior cases, by immersion of the threads, advantageously in the form of skeins or hanks, in the alkali solution, while allowing shrinking of the threads to occur. A mild tension can be used but the is dmitted. Other methods of contacting the alkaline solution withthe threads, such as spray i ing; running the threads over rollers wet with the solution, dripping the solution on the threads etc., can also be used. The time of contact of the solution with the threads, can vary between wide limits, e. g. a time of a few seconds'up' to several hours can be used, but it is to be understood that if the thread is not under tension, the amount of shrinkage will be very little after the threads have become thoroughly wetted with the solution. In other words, substantially all the shrinkage occurs immediately on completely wet-' ting the threads with the solution. 7

The amount of shrinkage varies with different silks, and different concentrations of the shrinking agent.

shrink more and may be more injured in dry and wet tenacity, and undergo more loss of luster,

when treated with a given concentration'of alkali than a commercially produced Lilienfeld silk of the same initial dry tenacity when treated with A Lilienfeld silk produced in the 4 laboratory having a given dry tenacity, also may while a similar commercial'sample of Lilienfeld v the ordinary kind.

Three samples of laboratory made Lilienfeld silk, treated respectively with NaOH solutions of 6%, 7% and 10%, showed a great loss of luster in all cases, no considerable loss in softness, the feel of the treated products being good, (no substantial loss of silky feel);

The following table shows some of the measurements of four tests made in accordance with the invention. The Lilienfeld'silk, in the form of out of the alkaline solution and immersedin a- 10% H2804 at 15 C., for 5 minutes. Then the silk was well washed in cold water and dried. No

tension was put upon the silk at any part of the coated with albumen, starch, gelatin or other protective sizing). In the claims, the term threads is intended to cover-such materials.

The following example is given, for the purpose of illustration.

Factory made viscose silk, made according to the process of Example I of my Reissue Patent 18,170, in the form of previously moistened skeins, is introduced, without tension, into a deep bath of aqueous solution of NaOH, of 6.4% strength, at ordinary temperature, say 15 to 20 C. After standing for about 2 minutes, the skeins are raised from the liquor, allowed to drain for about one minute, and then lowered into a deep bath of 10% H1304, allowed to stand for 5 minutes, then transferred to a washer in which the silk is well washed with cold or hot water, and dried. No tension is applied during the process. The ,extensibility is increased without any considerable loss of dry and wet tenacity or silky feel. The luster is slightly lowered.

The details of the operation can vary between wide limits. w I have referred above to'the use of the shrinking agent in a cold state. It is in no waynecessary that the said solution be used cold. It can be used warm or hot. But if used at or near boiling temperature, it is advisable to limit the time of contact of the threads with the liquor, to

essarily an objection. In fact it is known in the art to add pigments, etc. to viscose, before spinning the same in order to make delustered (or low luster) artificial silk, since often the very high luster of viscose silk is objectionable. Ac-

cordingly the decrease in luster produced in the present process may be in some cases a desirable feature.

I prefer, in the present invention, to use NaOI-I solutions of about 5.4 to 7%. I

As in my copending cases noted above, neutral salts, alkaline salts, organic materials, known in the mercerizing industry, can also be added to the shrinking solutions. Examples of such materials are sodium salts (chloride, nitrate, 'su1- phate, silicate, etc.) and the corresponding potassium salts, glycerine, alcohol, sugars, etc.

The process is applicable to filaments, fibers,

yarns, threads, woven, knitted or netted fabrics composed of the same. Also mixed goods can be similarly treated, (any silk, wool or other animal fibers or yarns thereof being preferably first treatment. The luster of the commercial sample about 5-10 minutes, as a longer treatment, hot, was not greatly damaged. The luster of the s'ecmight cause more injury to the tenacity. In or- 0nd and third samples was greatly reduced. The dinary cases, I prefer to use the solution cold, luster of the fourth, after treatment, was about hich is less troublesome, it not being necessary like mercerized cotton, (1. e. still greater reduced to heat the liquors. It was rather surprising to than the luster of the second and third sample). find thatalkaline shrinking agents could be 'used Dry tenacity Wet tenacity Ertensibility i I I Silk treated fl Before After Before After Before After Percent Percent Percent Commercial 6.4 5.444 3.872 3.967 2.864 6. 5 11.9 5 5.177 a. 151 3.413 1.808 4.7 13.2 7 4.353 2.103 2.510 1.857 5.2 17.5 Laboratory... 10 4.435 1. 525 2. 758 9.145 57 12.2

Loss of luster, or decrease in luster, is not n'eccold, in view of the fact that in some of my early jurious to said silk than warm or hot solutions,

(cf. Ser. 367,150 new Patent 1,989,101).

The difference in behaviour between the facone hand and the laboratory made Lilienfeld silk on the other, is probably due in large part at least, to the fact that the factory spinning machinery;

gives a more regular stretching than the laboratory machinery.

I claim:--- r a 1. Process of treating commercially produced viscose threads having a dry tenacity substa ntial- 1y exceeding 2 grams per denier but a low extensibility, which comprises subjecting said threads: to the action of a caustic alkali solution having a concentration above 5% but below 10%, calculated as NaOH, while allowing shrinkage of the threads to occur whereby the extensibility of said threads is substantially increased.

.2. Process of treating factory made viscose threads having a dry tenacity substantially exceeding 2 grams per denier but a low extensibility,

tory made Lilienfeld silk referred to above on the which comprises subjecting said threads to the ac-/ tion of a caustic alkali solution having a concentrationbetween about 5.4% and about 9%, calculated as NaQI-I, while allowing shrinkage of the threads to occur whereby the extensibility of said threads is substantially increased.

' 3. Process of treating factory made viscose threads. having a dry tenacity substantially exceeding 2 grams per denier but a low extensibility, which comprises subjecting said threads to the action of a caustic alkali solution having a concentration between about 6% and about 7%, calculated as NaOH, while allowing shrinkage of the threads to occur whereby the extensibility of said threads is substantially increased.

4. Process of treating factory made Lilienfeld silk, which comprises subjecting said threads to the action of a'caustic alkali solution having a concentration above 5% but below 10%, calculated as NaOH, while allowing shrinkage of the threads to occur whereby the extensibility of said threads is substantially increased.

I 5. As a new product, artificial threads'produced from viscose, said threads having a dry tenacity not below 2 grams per denier, and an extensibility at least 8%, and having a reduced degree of luster as compared with ordinary fac-" tory made Lilienfeld silk, which product can be' "produced by treating factory made Lilieni'eld silk with caustic alkali solution of about 5.4% to about 9% concentration, calculated as NaOH, and allowing permanent shrinking of the, same to occur during said treatment.

6. A process of treating Lilienfeld silk made on v a commercial scale, which comprises subjecting .the same to the action of a shrinking agent which has a shrinking action about equal to that of NaOH solution of over 5% but below 10% strength, and which does not have a substantially greater deleterious action on the dry and wet tenacity and soft silky feel, than NaOH solution of said concentration, while allowing shrinkage of the threads to occur.

LEON LILIENFELD. 

